/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.calcite.rel.metadata;

/**
 * Exception that indicates that a cycle has been detected while
 * computing metadata.
 */
public class CyclicMetadataException extends RuntimeException {
  /** Singleton instance. Since this exception is thrown for signaling purposes,
   * rather than on an actual error, re-using a singleton instance saves the
   * effort of constructing an exception instance. */
  @SuppressWarnings("ThrowableInstanceNeverThrown")
  public static final CyclicMetadataException INSTANCE =
      new CyclicMetadataException();

  /** Creates a CyclicMetadataException. */
  public CyclicMetadataException() {
    super();
  }
}

// End CyclicMetadataException.java
